Suppressors are well-known in the armaments field for reducing blast pressure and flash incident to the firing of a gun. Such suppressors, when assembled to the muzzle of a gun, are effective to muffle the sound and blast pressure wave produced by the projectile as it travels through the gun bore and exits the muzzle of the gun barrel. The blast pressure wave of a 50 calibre rotary machine (Gatling) gun, for example, is particularly forceful and has been known to crack windows of aircraft from which it is being fired. Flash suppression is also an extremely important consideration to minimize detection of the gun position by the enemy, particularly during night fighting. In addition, gun flash readily saturates night vision equipment, thus severely degrading the utility of this equipment for gun operators under low light battle conditions.
Unfortunately, the assembly of a suppressor to the muzzle of a gun barrel, which heretofore has been essentially a fixed assembly, adds at least five inches of barrel length in the case of a 50 calibre rotary machine gun. This extra barrel length presents problems due to the traditionally close confines of military vehicles in which the gun is installed. For example, rotary machine guns are installed in combat helicopters to fire from side opening doors. Normally, the guns are stowed inside the helicopters, but in battle, they are moved into firing positions protruding through the open helicopter doors. In many helicopter installations, the extra barrel length caused by the suppressor assembly interferes with the door frame of the helicopter during designed gun movements between firing and stowed positions. Consequently, the utilization of blast pressure and flash suppressors on rotary machine guns installed as side-firing armaments in combat helicopters is precluded in the case of many existing combat helicopter designs.